It is well-known to make flat parts from larger sheets of material by trimming the sheets to form the part's outline. This kind of operation occurs in many different manufacturing environments, ranging from residential construction, where sheets of plywood are routed to form the outline of windows and doors, to the aircraft industry where sheets of aluminum, or in some cases, composite materials, are routed to form flat stock that is later used as an aircraft part.
The present invention was developed for the purpose of improving certain trimming/routing operations at a Canadian manufacturing facility owned by The Boeing Company in Winnipeg, Manitoba. There, many flat parts are made from relatively thin, molded sheets of composite material. Making the parts first involves placing a template across a given sheet, the template defining the part's outline or perimeter. This is followed by cutting or trimming around the sheet around the template to create the part.
Prior to the development of the present invention, it has been the practice at Boeing to clamp the template to the sheet by using conventional "C" clamps, so that the template cannot move relative to the sheet as its is subsequently trimmed. Trimming is typically done by a hand-held router whose cutting path is guided by the template's outer edge.
The use of "C" clamps to hold templates has always been troublesome in this particular manufacturing environment because of the large numbers of parts being made. The clamps interfere with routing, because the edge of the template is typically positioned inside the "C" of the clamp. Therefore, at one time or another, each clamp blocks router travel along the template's edge. As a result, each clamp must be removed when it gets in the way, temporarily stopping further routing, and later re-attached after the router has passed.
The present invention was designed to overcome the above-described clamp interference, and consequent slowing of trimming/routing that is caused thereby. As will become apparent, the invention provides a system for fixedly holding a template relative to a workpiece, but at the same time, leaves the template's outer edge free for routing around its perimeter without interference. Just how the invention accomplishes this will become understood upon consideration of the following.